Arrangement for raising and lowering or retaining the inductor in its upper most position in equipment

ABSTRACT

An improved apparatus for hardening elongated workpieces of the type having a pair of indexable spiders with centers for holding the workpieces as they are successively indexed through consecutive treating stations, a slotted plate which is mounted for rotation with the workpieces, a roller which moves on a curve generated by a four-bar linkage working in the slots, a cam disc rotating as the roller moves and having a cam contour which cooperates with a follower roller on a lifting arm for a heating inductor at one of the stations and means for locking the lifting arm in a position with the inductor withdrawn. The locking means includes a second cam member which also engages the lifting arm and control switches for causing the second cam member to prevent the inductor from returning to its station when no workpiece is being advanced to the inductor station.

United States Patent [191 vReinke et al.

[451 Feb. 25, 1975 Stengel, Wuppertal-Hahnerberg, both of Germany [73] Assignee: AEG-Elotherm GmbH, Postfach,

Germany [22] Filed: Sept. 12, 1973 [21] Appl. No.: 396,472

[30] Foreign Application Priority Data 4/1969 Reinke et a1 219/1069 3,653,268 4/1972 Diepeyecn 74/55 3,664,203 5/1972 Pataki 74/55 3,732,741

5/1973 Defontenay 74/55 Primary Examiner-Wesley S. Ratliff, Jr. Attorney, Agent, or Firm-Cushman, Darby & Cushman [5 7] ABSTRACT An improved apparatus for hardening elongated workpieces of the type having a pair of indexable spiders with centers for holding the workpieces as they are successively indexed through consecutive treating stations, a slotted plate which is mounted for rotation with the workpieces, a roller which moves on a curve generated by a four-bar linkage working in the slots, a cam disc rotating as the roller moves and having a cam contour which cooperates with a follower roller on a lifting arm for a heating inductor at one of the stations and means for locking the lifting arm in a position with the inductor withdrawn. The locking means includes a second cam member which also engages the lifting arm and control switches for causing the second cam member to prevent the inductor from returning to its station when no workpiece is being advanced to the inductor station.

2 Claims, 1 Drawing Figure ARRANGEMENT FOR RAISING AND LOWERING OR RETAINING THE INDUCTOR IN ITS UPPER MOST POSITION IN EQUIPMENT The invention relates to an arrangement for raising and lowering or retaining the inductor in its uppermost position in equipment for inductively hardening elongated workpieces which are mounted between centers on the arms of a pair of spiders indexable into several consecutive treating stations by a slotted plate which is mounted with the spiders and coaxial therewith, a roller which moves on a curve'generated by a four-bar linkage working in the slots, while the shaft driving one crank of the linkage carries a substantially reniform cam disc of which the peripheral cam contour cooperates with a follower roller on a lifting arm which carries the heating inductor, and which extends within range of a locking means.

Equipment of this kind is discussed in detail in US. Pat. No. 3,441,703. When in such equipment a workpiece has been inductively heated a geared motor coupled to the drive shaft of the four-bar linkage is started and by rotation of the reniform cam disc which is mounted on the drive shaft the lifting arm is first raised so that the inductor which is carried by the lifting arm is also raised and thus withdrawn from the workpiece. During further rotation of the drive shaft the pair of spiders is indexed for instance through an angle of 120 to transfer the workpiece which has just been heated into a quench and at the same time to move another workpiece which has been mounted between two centers into position to be heated under the inductor. Continued rotation of the drive shaft and of the cam disc it carries finally results in the inductor being relowered over the fresh workpiece for heating the same.

For diverse reasons, for example, as a result of a stoppage in the supply of the workpieces to the loading station where the workpieces are gripped by the spider arms, or because a workpiece is incapable of being properly supplied at a reduced rate, a workpiece may not be present between the pair of carrier arms which are about to be indexed to the heating station. When this situation arises, the inductor should be prevented from being lowered and possibly colliding with the centers which in the absence of a workpiece may project some distance into the path of the inductor.

In a modification of the equipment described in US. Pat. No. 3,441,703, the lifting arm for raising the inductor is arranged to be lockable by a spring-loaded detent which is retained in inoperative position by an electromagnet. When a switch or sensor located between the centers at the loading station detects the absence of a workpiece, the switch or sensor causes the electromagnet to be deenergized and the detent to be propelled under the lifting arm by its spring, thereby preventing the arm from descending and lowering the inductor. I

This device for locking the inductor by means of a detent is capable only of keeping the inductor in a position determined by the position of the detent. When the position of the inductor is to be adjusted this limitation is felt to be a defect.

It is the object of the present invention further to im prove such apparatus by adding means for lifting and lowering the inductor respectively, keeping it in its uppermost position in equipment for inductively heating elongated workpieces in which the workpieces are gripped between centers on the arms of a pair of spiders, indexed consecutively to several treating stations,

and in which, independently of the movement of the spiders, the inductor can be raised and lowered and retained at any desired distance from the workpiece.

According to the invention, this is achieved by locking means consisting of a second cam disc which is mounted on a drive shaft and driven by a geared motor, the cam contour having a radius which is a monotonous function of the cam angle within a given angular range and the second cam disc cooperating with a second follower roller mounted on the lifting arm. Preferably, the improved apparatus includes control means comprising limit switches for controlling the rotation of the second cam disc from a first angular end position to a second angular end position.

Furthermore, in a desirable embodiment of the proposed arrangement the control means comprise switching elements for interrupting and reversing the rotation of the second cam disc in any possible angular position.

The invention will now be more particularly de scribed with reference to the drawing which is a schematic side elevational representation of equipment according to the invention:

The upper ends of two radial carrier arms 1 and l of a pair of spiders mounted in a machine frame can be seen in the drawing and workpieces 2 and 2 are understood to be mounted between centers (not shown) on cooperating carrier arms. A slotted plate 3 is rigidly connected to the pair of spiders, three slots 4, 5 and 6 extending radially from the center of the plate at relative angular intervals of In the position of the spiders shown in the drawing, the workpiece 2 which is gripped by the centers of the pair of carrier arms 1 is in heating position under an inductor 7 which is mounted on the end of a lever arm 8. This lever arm 8, which also carries the transformer 9 required for feeding the inductor 7, is mounted on a shaft 10 rotatably mounted in the machine frame. The'movements of the lever arms 8 and hence of the inductor 7 are controlled by a lifting arm 11 which is likewise mounted on the end of shaft 10, whereas its free end carries a follower roller 12 adapted to ride on the circumference of a substantially reniform cam disc 13 which is mounted on a shaft 15 rotating in hearings in the machine frame. This shaft 15 which can be driven by a motor 16 and a worm gear transmission (not shown) simultaneously serves for driving a four-bar linkage comprising a crank 20 affixed to shaft 15, an oscillating arm 17 mounted in the machine frame, and a link 14 which is pivotably attached to the crank 20 and to the oscillator 17. In the course of each full revolution of the shaft 20 a roller 18 which is mounted on the link and engages the slots in the slotted disc 3 moves in a loop 19 which comprises two path sections extending roughly radially from and to the disc center.

When the pair of spiders is in the position shown in the drawing, the workpiece 2 which revolves on centers underneath the inductor 7 is in course of being inductively heated. When the inductor current is switched off, for instance by a time switch, the motor 16 is started, automatically or manually, and turns the shaft 15 together with the reniform cam disc 13 in the clockwise direction, the cam follower l2 riding on the circumference of the cam. Since the radius under the rol ler 12 first increases, the follower roller 12 and the lifting arm are first lifted and the inductor 7 which is connected to them by the shaft and the arm 8 is swung away from the workpiece 2 which is has heated. When in course of the rotation of the cam 13 point c on its circumference moves under the follower roller 12 the inductor 7 will have reached its highest point. While the cam 13 revolves under the roller 12 from point a to point c the slotted plate 3 and hence the spiders remain stationary because during this period the roller 18 of the linkage will move from point a to point b along a linear path section which is roughly a radius of the slotted disc 3. Consequently the disc 3 will not be rotated.

During the ensuing roughly half revolution of the shaft 15 in which the follower roller 12 rides from point 0 to point b on a constant radius peripheral path and thus keeps the inductor in its fully raised position, the roller 18 of the four-bar linkage travels from b to 0 and thus indexes the slotted disc 3 counterclockwise through an angle of 120. Consequently, the workpiece 2 which is mounted between the centers of the spider arms 1 will be lowered into a tank containing a quench, whereas the workpiece 2 between the centers of the next pair of radial arms 1 is carried into heating position under the inductor 7. During the remainder of the full revolution of the shaft 15 in course of which the cam 13 turns under the follower roller 12 from point b back to starting position a in which it is stopped by a limit switch inactivating the motor 16, the inductor 7 is returned into its heating position above the fresh workpiece 2' by the lowering of the lifting arm 11. At the same time, the slotted disc 3 remains stationary as the roller 18 of the linkage descends from point 0 along a radius back to the center a of the slotted disc 13.

According to the present improvement there is provided, for lifting and lowering respectively the inductor independently of the drive of the spider, a shaft 22 which is reversibly drivable in bearings in the machine frame by a geared motor 21, and which carries a second cam disc 23. This cam disc 23 which cooperates with a second follower roller 24 mounted on the lifting arm 11 has a cam contour having a radius which, within a predetermined angular range, increases as a monotonous function of its angle of rotation.

The lifting arm 11 is locked by means of the second cam disc 23 as follows. While the workpiece 2 between the centers on the radial spider arms 1 is being inductively heated, the next workpiece 2 is gripped between the centers of the arms 1, the workpiece being presented to them in this position. If now, for any reason whatsoever, a workpiece should not have been mounted or, if the presented workpiece has not been gripped because it differs too much from its required shape, then the absence of the workpiece is detected by a switch or sensor 30 and a corresponding signal is generated. The effect of this signal is that at the end of the inductive heating of the workpiece 2, the motor 21 will be started at the same time as the motor 16 for driving the cam disc 13. The motor 21 therefore rotates the cam disc 23 counterclockwise at a speed which is low enough to avoid contact between the cam disc 23 and the follower roller 24 on the lifting arm 11 during the raising of the lifting arm 11 by the cam disc 13. Not until the lifting arm 11 and hence the inductor 7 have arrived in their uppermost positions will the cam 23 catch up with and make contact with the follower roller 24 on the lifting arm 11. A suitably located limit switch 32 switches the motor 21 off at this instant and thus stops the further rotation of the second cam disc 23. The lifting arm 11 and the inductor 7 are thus locked in their upper positions by the cam 23 irrespectively of the continued operation of cam disc 13.

At the end of the operating cycle, i.c. at the end of the full revolution of cam 23 further inductive heating cannot be initiated because the inductor 7 is locked in its upper position and the switching on of the inductor current is prevented by the operation of suitable limit switches (not shown). Now assuming that a workpiece is presented at the loading station and that it has been gripped by the centers; then a fresh cycle will be initiated by the starting of the motor 16 and when rotation of the cam has taken point c underneath the follower roller 12 of the lifting arm 11, motor 21 will also be started under the control of a suitable limit switch to rotate the second cam 23 clockwise into its starting position shown in the drawing. The further movements and events in the operating cycle will then proceed as in a normal case.

Apart from retaining the inductor 7 in its raised position, the second cam 23 serves the additional purpose of moving the inductor 7 into any desired position be tween its position for heating and its inactive position when fully raised, for instance for purposes of adjustment. This is done by keeping the cam 13 stationary in its starting position and raising the lifting arm 11 by rotating the cam 23 which will now make continuous contact with the roller. For this purpose, the control system comprising the limit switches for controlling rotation of the second cam 23 is equipped with overriding switch means 34 which permit rotation of this second cam 23 to be stopped or reversed in any angular position.

What is claimed is:

1. In apparatus for raising and lowering or retaining an inductor in its uppermost position in equipment for inductively hardening elongated workpieces which are mounted between centers on the arms of a pair of spi ders indexable into several consecutive treating stations by a slotted plate which is mounted for movement with the spiders and coaxially therewith, a roller which moves on a curve generated by a four-bar linkage working in the slots, while the shaft driving one crank of the linkage carries a substantially reniform cam disc of which the peripheral cam contour cooperates with a follower roller on a lifting arm which carries the heating inductor, and which extends within range of a locking means, the improvement wherein the locking means comprises a second cam disc mounted on a drive shaft and drivable by a geared motor, the cam contour having a radius which within a predetermined angular range increases as a monotonous function of the cam angle and the cam cooperating with a second follower roller mounted on the lifting arm, means for sensing the absence of a workpiece for mounting on said spider and producing a signal responsive thereto to operate said geared motor to rotate said second cam disc, and limit switch means for stopping said geared motor at a predetermined angular position in which said lifting arm is held out of operative contact with said reniform cam disc.

2. In apparatus as in claim 1, the further improvement wherein the control means comprise switching elements for interrupting and reversing the rotation of the second cam disc in any possible angular position. 

1. In apparatus for raising and lowering or retaining an inductor in its uppermost position in equipment for inductively hardening elongated workpieces which are mounted between centers on the arms of a pair of spiders indexable into several consecutive treating stations by a slotted plate which is mounted for movement with the spiders and coaxially therewith, a roller which moves on a curve generated by a four-bar linkage working in the slots, while the shaft driving one crank of the linkage carries a substantially reniform cam disc of which the peripheral cam contour cooperates with a follower roller on a lifting arm which carries the heating inductor, and which extends within range of a locking means, the improvement wherein the locking means comprises a second cam disc mounted on a drive shaft and drivable by a geared motor, the cam contour having a radius which within a predetermined angular range increases as a monotonous function of the cam angle and the cam cooperating with a second follower roller mounted on the lifting arm, means for sensing the absence of a workpiece for mounting on said spider and producing a signal responsive thereto to operate said geared motor to rotate said second cam disc, and limit switch means for stopping said geared motor at a predetermined angular position in which said lifting arm is held out of operative contact with said reniform cam disc.
 2. In apparatus as in claim 1, the further improvement wherein the control means comprise switching elements for interrupting and reversing the rotation of the second cam disc in any possible angular position. 